In the field of computerized energy management in large buildings energy conservation is very important. The systems used presently utilize a distributed computing approach to control heating, ventilation and some lighting management. In addition, some systems may incorporate miscellaneous functions such as security monitoring and control, and fire and burglar alarm management. In many buildings, control and monitoring are performed by a centralized computer connected to the network. The central computer may actually reside in a remotely located building and communicate via telephone, satellite, or other means. The connections within the network itself may include multiple media, including a twisted pair or coaxial wiring, power line signaling, fiber-optic cabling and rf links. Networks of this type do not necessarily need a centralized control computer to coordinate activities.
It is possible to organize a network so that it serves as a means for communication between micro-controllers distributed throughout the building. In this approach their actions are coordinated by their internal control programs. An example of this would be a case whereby a switch closure signal sent to one luminaire to energize its lamps is then relayed by its micro-controller over the network to a number of other luminaries to energize them as well. This discussion assumes that a central computer performs the principal control and monitoring functions of a energy management system.
The state of the art micro-controllers networks being used are LonWorks.RTM., and CEbus.RTM.. The micro-controller devices are embedded within the equipment being controlled and is distributed across a building on a network that may consist of different topologies including a star, ring and point to point topologies. The prior art as described in U.S. Pat. No. 5,381,078 entitled "Control and Communication Processor Potentiometer System for Controlling Fluorescent Lamps", is one such control system. This control system uses a distributed LonWorks.RTM. micro-controllers containing electronic potentiometers mounted on a wall and lighting controllers mounted on ceiling to set the dimming level of a number of dimmable slave ballasts under its control. However, the control system does not sense ballast parameters.
The following is a discussion of the dimming ballast circuitry, its means of dimming control, and its interface to the embedded micro-controller. The discussion centers around a design that uses the ML4832 integrated circuit (IC) ballast controller chip made by MicroLinear, 2092 Concourse Drive, San Jose, Calif. 95131. This IC is similar to that described in U.S. Pat. No. 5,315,214, entitled "Dimmable High Power Factor High-Efficiency Electronic Ballast Controller Integrated Circuit with Automatic Over-Temperature Shutdown", by Lesea, dated May 24, 1994. This IC combines power factor correction functions and ballast control in one IC. Approaches using other IC devices should be obvious to those skilled in the art. Sectioned schematic diagrams will be shown for clarity is describing the essential points of the invention, the details not explained can be found by referencing the MicroLinear literature.
Next, the system for dimming a fluorescent light is described in U.S. Pat. No. 3,697,821. In the aforementioned patent, a semiconductor multiple remote control unit have been used to switch and dim lights. A remote control unit is provided for individually and independently controlling the brightness of the lamps independently controlling the operation of a common lamp dimmer unit by turning on and off the dimmer unit and controlling the brightness of the lamps independently of previous settings or condition of the remote control units. A three wire conductor system is used to connect the various remote control units that are in parallel to one another.
The next prior art invention relates to controlling a household lighting circuit, U.S. Pat. No. 4,733,138. The aforementioned patent is a programmable lighting circuit controller for controlling a plurality of household lighting circuits. The invention includes a microprocessor and an electronically erasable programmable read-only memory for programming household lighting circuits for a variety of loads. One of the lighting circuits may include fluorescent loads by using a heater circuit for the fluorescent lamps. The microprocessor is controlled to raise and lower lighting levels, set lighting levels in memory and recall preset levels from memory, as well as to provide heating for fluorescent lights.
The prior art inventions are all related to controlling the light by either electronic potentiometers, semiconductors or a microprocessor with an erasable read only memory. However, the prior art does not use the lighting circuitry to control the energy management in large buildings.
It is an object of this invention to provide an electronic lighting ballast that contains an interfacing means of connecting the ballast to a building computer network for the purposes of ballast control, ballast and luminaire monitoring of light output, energy usage, lamp current, and ballast temperature, environmental monitoring including nearby light levels, and room temperature, and control and monitoring of other nearby luminaries. Such a network can be interconnected to local utility companies so that lighting in large buildings can be selectively managed in times of high power demand to help balance system loading.
It would be advantageous to provide an electronic lighting ballast that contains a computer interface incorporating a micro-controller system to provide control and monitoring functions under operation of a program stored in its own computer memory.
It would also be advantageous to provide an electronic lighting ballast that contains within it means of powering said computer interface and micro-controller circuitry.
It would also be advantageous to provide an electronic lighting ballast that contains means for connection of light detection sensors, occupancy sensors, temperature sensors, and other environmental sensors that are located remote from the luminaire.
It would also be advantageous to provide an electronic lighting ballast that contains means for controlling and monitoring other nearby incandescent or gas discharge lighting luminaries, such means include control by means of the micro-controller contained within the luminaire, or control by commands obtained from the energy management control network.
It would also be advantageous to provide an electronic lighting ballast that contains means of identification to the control computer network, and means of identifying each luminaire under its control to the energy management control network.
It would also be advantageous to provide an electronic lighting ballast that contains within it means of modulating light for communication purposes, with data to be communicated being obtained from the distributed building control network through a computer interface means contained within the ballast unit.
It would also be advantageous to provide an electronic lighting ballast that has the above control, and monitoring features, but the computer interfacing and micro-controller circuitry is located nearby the luminaire so that it contains its identity to the building computer network.